The present invention relates to a process for the preparation of epoxides by electrochemical oxidation of allyl alcohols in the presence of alkanols and an auxiliary electrolyte or by the reaction of allyl alcohols with halogen in the presence of alkanols in an alkaline medium, and to novel epoxides.
J. Chem. Soc. 1393-1395 (1948) discloses the reaction of chlorine with allyl alcohol in an acid medium to yield 2,3-dichloropropanol. According to Houben-Weyl, Vol. 5/4, 4th Edition, pp. 55 to 58 and 133 to 141, bromohydrins can be produced under comparable conditions by reacting allyl alcohols with bromine or bromine having the degree of oxidation (+1).
According to Houben-Weyl 5/3, 4th Edition, pp. 775 et seq and Houben-Weyl 5/4, 4th Edition, pp. 141-146, the reaction of olefins with chlorine or chlorine having the degree of oxidation (+1) or with bromine or bromine having the degree of oxidation (+1) in the presence of alcohol yields, on the other hand, halohydrin ethers.
The synthesis of 3-substituted 3-hydroxy-1 ,2-epoxides from 3-substituted alk-2-en-1-ols is only possible, according to Tetrahedron Lett. 27, 4987-4990 (1986) and Chem. Lett. 645-646 (1988), via a separate stage involving the isomerization of the initially synthesized 3-substituted 1 -hydroxy-2,3-epoxides, or, as described in Helv. Chim. Acta 54, 1822-1845 (1971), the isomerization is carried out at the allyl alcohol level.
The direct synthesis of 3-hydroxy-1,2-epoxides or 3-alkoxy-1,2-epoxides from 1 -hydroxyalk-2-enes where the oxygen atom in the educt becomes the epoxide oxygen atom of the product has not yet been disclosed.
It is thus an object of the invention to provide such a method of direct synthesis.